Common Name

Robe’s Wattle

Family

Fabaceae

Distribution

Occurs near Marble Bar and Pardoo Stn S to Ethel Creek Stn in the Pilbara region, extending E to Rudall River Natl Park in the Little Sandy Desert, W.A. Possible disjunct occurrence on Barrow Is.

Description

Openly branched, multistemmed, glabrous shrub 2–3 m high. Bark grey on main stems, light bronze on upper branches, smooth. Branchlets yellowish to pale orange-brown or bronze. Stipules spinose, normally absent or infrequent on mature plants, 1.5–3 (–4) mm long. Phyllodes linear to narrowly oblong or linear-oblanceolate, 15–25 (–35) mm long, (1–) 2–3 (–4) mm wide, l:w = (5–) 6–10 (–14), bright green, thick and fleshy (breaking with a clean snap when fresh), wrinkled when dry; midrib obscure or not evident; gland ±basal, not prominent, 0.4–0.5 mm long. Inflorescences simple, 1 per axil, initiated synchronously with phyllodes on new shoots; peduncles (8–) 10–17 mm long; heads globular, 40–60-flowered, golden. Flowers 5-merous; sepals free, linear-spathulate. Pods oblong to narrowly oblong, flat but rounded over seeds along midline, (1.5–) 2.5–4 (–6) cm long, 6–8 (–9) mm wide, chartaceous. Seeds transverse, oblong to elliptic, ovate or round, 3–4 mm long, ±dull, black or sometimes obscurely mottled dark brown; funicle short, thick; aril small.

Phenology

Flowers Aug.–Sept.

Habitat

Grows in sand or loam over granite, laterite or quartz, in spinifex grassland, sometimes along drainage lines.

Specimens

W.A.: 4.5 km S of Parngurr, Little Sandy Desert, P.K.Latz 17826 (NT n.v., PERTH); 8 km E of Nullagine R., E of Marble Bar, B.R.Maslin 8466 (PERTH); Barrow Is., B.R.Maslin 8804 (PERTH); Upper Rudall R. area, 20 Nov. 1971, M.McInnes (PERTH); 5 km NW of Shay Gap Settlement, L.Thomson LXT 1180E–I (all PERTH).

Notes

Acacia robeorum was treated as a narrow phyllode variant of A. synchronicia by B.R.Maslin in Fl. Australia 11A: 379, fig. 40U–W (2001).

A member of the ‘A. victoriae group’, most closely related to the more widespread A. synchronicia with which it is sometimes sympatric but which is most readily distinguished by its commonly pruinose branchlets, generally longer stipules, grey-green to glaucous, often broader, thinly textured phyllodes (which are not wrinkled when dry and which do not break with a clean snap when bent when fresh), generally broader pods and more commonly mottled seeds; further differences are discussed in B.R.Maslin & S.van Leeuwen, Nuytsia 18: 164 (2008).

FOA Reference

Flora of Australia Project

Author

B.R.Maslin, J.Reid